PARENT SESSION
Symposium 11: Digging Deeper or Scratching the Surface? Exploring Ecological Theories in Urban Soils.
Organized by: M Pavao-Zuckerman and L Byrne
Wednesday, August 4, 8:00 AM to 10:30 AM, Oregon Ballroom 203.

Urban influences on resource availability for decomposers in remnant forests: Implications for nutrient cycling.

Carreiro, Margaret^*,1, ¹ University of Louisville, Louisville, KY

ABSTRACT- Comparative studies of forests along urban-rural land-use gradients in several cities have shown that conditions in the built environment are associated with altered soil processes in urban forest remnants compared with suburban and rural reference stands. Proximate explanations for trends in C and N mineralization along these gradients include differences in within species and community-level leaf litter quality, increased atmospheric inputs of inorganic resources, and changes in relative abundance of different decomposer functional groups. Results of studies in several cities will be brought together to examine decomposer activity responses to the following incipient patterns involving carbon quality and C:N:P ratios in plant and soil substrates: 1) variation in within-species leaf litter quality associated with urban atmospheric chemistry and microclimate, including those due to altered nitrogen and phosphorus retranslocation in senescent leaves; 2) lability and high N and P content of invasive tree litters; 3) increased atmospheric deposition of nitrogen and basic cations; and 4) transformation of stratified moder soils to mixed mull soils by invasive exotic earthworms. It is safe to say that we are still scratching the surface in understanding how cities may alter nutrient cycling in urban forests. Furthermore, there is a need to dig much deeper if we are to open the black box surrounding plant root responses to urban conditions and their effects on decomposers and nutrient cycling. Prioritizing research questions and conducting parallel cooperative studies in urban forests in different cities would accelerate our ability to distinguish which forest response patterns are common across cities from those that are idiosyncratic to particular cities.

Key words: soil decomposers, nutrient cycling, urban-rural gradients, urban forests